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Early transition metal complexes bearing a C-capped tris(phenolate) ligand incorporating a pendant imine arm: synthesis, structure, and ethylene polymerization behavior

journal contribution
posted on 04.09.2014, 14:59 by Damien Homden, Carl Redshaw, Joseph A. Wright, David L. Hughes, Mark ElsegoodMark Elsegood
The ligand 3-[2,2′-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-(2,6-diisopropyl)phenylimine] (L1H3) was reacted with MCl4 (M = Ti, Zr) or MCl5 (M = Nb, Ta) to give complexes of the type [MCl2(L1H2)2] (M = Ti (1); Zr (2)), [NbCl3(L1H)] (3), or [TaCl4(L1H2)] (4), respectively. Single crystal X-ray diffraction of 1−4 revealed common “iminium” species resulting in zwitterionic complexes. Reaction of [V(Np-tol)(On-Pr)3] with L1H3 afforded [{(VNp-tol)(L1H)}2(µ-On-Pr)2] (5), and a second complex [(VO)2(µ-O)(L3H)2] (6) (L3H being derived from 3-[2,2′-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-p-tolylimine]). The condensation reaction between 3-[2,2′-methylenebis(4,6-di-tert-butylphenol)-5-tert-butyl-2-hydroxybenzaldehyde] (L0H3) and o-phenylenediamine (1,2-diaminobenzene) afforded two products: a pseudo-16-membered hydrogen bonded macrocyclic structure {1,2-bis-3-[2,2′-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-benzyldiimine]} (L5H6), or the benzimidazolyl bearing ligand (L6H3). The reaction of L5H6 or L6H3 with [VO(On-Pr)3] under varying conditions produced the complexes [(VO)(L5H4)] (7), [(VO)2(L5H)] (8), or [VO(L6H2)2] (9). L0H3 was reacted with a number of anilines to give the proligands {3-[2,2′-methylenebis(4,6-di-tert-butylphenol)-5-tert-butylsalicylidene-R-imine]}, where R = NC6H5 (L2H3), NC6H4-Me (L3H3), and NC6H2-Me3 (L4H3). Reactions of these ligands with [VO(On-Pr)3] formed bischelating complexes of the form [(VO)(L2−4H2)2] (10, 11, and 12, respectively). The reaction of L1H3 with trimethylaluminum led to a bis-aluminum complex {(AlMe2)[AlMe(NCMe)]L1} (13). The ability of complexes 1−12 to polymerize ethylene in the presence of an organoaluminum cocatalyst was investigated. Procatalysts 1 and 2 were found to produce negligible activities in the presence of dimethylaluminum chloride (DMAC) and the reactivator ethyltrichloroacetate (ETA), whereas 3 and 4 were found to be completely inactive for polymerization using a variety of different organoaluminum cocatalysts. Using the combination of DMAC and ETA, complexes 5−12 were found to be highly active catalysts; in all cases, the polymer formed was of high molecular weight linear polyethylene.


The University of East Anglia and the EPSRC are thanked for financial support. We thank the EPSRC Mass Spectrometry Service Centre (Swansea, U.K.). The EPSRC X-ray Crystallography Service, Southampton, U.K., is thanked for data collection of 13, and the EPSRC is also thanked for the award of beamtime at Daresbury Laboratory (Station 9.8 SMX) and Drs. John Warren and Tim Prior for scientific support. We would also like to thank Rapra Scientific Ltd. for GPC measurements and Dr Myles Cheesman (UEA) for help with recording EPR spectra.



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  • Chemistry

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5799 - 5814 (16)


HOMDEN, D. ... et al., 2008. Early transition metal complexes bearing a C-capped tris(phenolate) ligand incorporating a pendant imine arm: synthesis, structure, and ethylene polymerization behavior. Inorganic Chemistry, 47 (13), pp. 5799 - 5814.


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